Heat shield assembly and method
A heat shield assembly including a skin panel and a stiffener including a base portion and a bead portion protruding from the base portion, wherein the base portion is connected to the skin panel to define a bead volume between the bead portion and the skin panel.
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This application relates to heat shields, such as heat shields on aircraft, and, more particularly, to stiffening of heat shields.
BACKGROUNDAn externally mounted aircraft engine is typically attached to the associated aircraft by a pylon. As one example, the pylon may couple the engine to a wing of the aircraft (e.g., the engine may be suspended below the wing by way of the pylon). As another example, the pylon may couple the engine directly to the fuselage of the aircraft (e.g., the pylon may extend between the engine and the side of the fuselage proximate the rear of the fuselage). For aerodynamic purposes, the pylon is typically housed within a fairing.
Due to proximity with the aircraft engine, particularly with the hot exhaust gases emanating from the aircraft engine, a pylon fairing typically includes a heat shield. For example, the aft pylon fairing on a commercial aircraft can include a heat shield as a subcomponent thereof. A typical heat shield includes skin panels attached to frame members to define an internal volume/compartments. The internal volume/compartments of the heat shield may be filled with a thermal insulation material.
The skin panels of a heat shield are formed from various heat-resistant materials, such as aerospace-grade titanium alloys. Nonetheless, the skin panels of a heat shield may be susceptible to buckling when heated, particular on larger aircraft where the distance between adjacent frame members is greater.
Accordingly, those skilled in the art continue with research and development efforts in the field of aircraft heat shields.
SUMMARYIn one embodiment, the disclosed heat shield assembly may include a skin panel and a stiffener including a base portion and a bead portion protruding from the base portion, wherein the base portion is connected to the skin panel to define a bead volume between the bead portion and the skin panel.
In one embodiment, the disclosed method for stiffening a skin panel of a heat shield assembly may include the steps of (1) forming a blank into a stiffener including a base portion and a bead portion protruding from the base portion and (2) connecting the base portion to the skin panel.
Other embodiments of the disclosed heat shield assembly and method will become apparent from the following detailed description, the accompanying drawings and the appended claims.
The disclosed heat shield assembly 100 may be incorporated into an aircraft, such as a fixed-wing aircraft 10, as shown in
Referring to
As shown in
Referring to
A thermal insulation material 118 (
The frame members 110 may be spaced along a primary longitudinal axis X (
A cover 122 (
Because of the proximity to the exhaust jet 26 (
As shown in
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The protruding distance D (
As best shown in
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The length L (
As best shown in
The stiffener 112 of the disclosed heat shield assembly 100 may be formed from a material (or combination of materials) tolerant to relatively high temperatures. The material used to form the stiffener 112 may be the same as, similar or different from the material used to form one or more of the base skin panel 104, the side skin panels 106, 108 and the frame members 110. In one expression, the stiffener 112 may be formed from a metallic material, such as a titanium alloy. As one specific, non-limiting example, the stiffener 112 may be formed from Ti-6242 (Ti-6Al-2Sn-4Zr-2Mo) or a similar titanium alloy. In another expression, the stiffener 112 may be formed from a composite material, such as a ceramic composite.
As shown in
Connection between the stiffener 112 and the interior surface 148 of the base skin panel 104 may be made by way of the base portion 132 of the body 130 of the stiffener 112. Specifically, the base portion 132 of the stiffener 112 may act as a flange that facilitates connecting the stiffener 112 to the base skin panel 104. Therefore, when the base portion 132 is properly connected to the base skin panel 104, the bead portion 134 of the body 130 of the stiffener 112 protrudes outward from the base skin panel 104 and the base skin panel 104 encloses, at least partially, the bead volume 136.
Various techniques may be used to effect a connection between the base portion 132 of the stiffener 112 and the base skin panel 104. As one non-limiting example, the base portion 132 of the stiffener 112 may be connected to the base skin panel 104 by thermal joints 133, such as by welding, brazing or soldering, as shown in
Without being limited to any particular theory, it is believed that connecting a stiffener 112 having a bead portion 134 directly to a skin panel 102 of a heat shield assembly 100, particularly to the base skin panel 104 of a heat shield assembly 100, may advantageously stiffen the skin panel 102, thereby may reduce (if not eliminate) the occurrence of buckling when the heat shield assembly 100 is heated, such as by the exhaust jet 26 of an engine 16, as shown in
Various techniques may be employed for forming the disclosed stiffener 112 depending on various considerations, including cost and the composition of the material being formed into the disclosed stiffener 112.
In one particular implementation, the disclosed stiffener 112 may be formed using a superplastic forming process. However, other suitable methods may be used to form the stiffener 112. As shown in
To effect the desired superplastic formation, the blank 150 (as well as the die 152 and the cover 154) is heated to a temperature at which the material of the blank 150 becomes superplastic. For example, when the blank 150 is formed from a titanium alloy, superplasticity of the blank 150 may be achieved by heating the blank 150 to a temperature ranging from about 1,450° F. to about 1,850° F. Once at the desired temperature, the blank 150 is formed against the die 152, such as by injecting a gas 156 (e.g., an inert gas/gas mixture) between the blank 150 and the cover 154 to urge the superplastic blank 150 against the die 152, as shown in
Referring to
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The location of a stiffener, the number of stiffeners used, the number of bead portions on a given stiffener, and/or the orientation of the bead portion may be selected to optimize the stiffeners for a particular application. Various combinations and variations are possible without departing from the scope of the present disclosure.
Examples of the disclosure may be described in the context of an aircraft manufacturing and service method 400, as shown in
Each of the processes of method 400 may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator may include without limitation any number of aircraft manufacturers and major-system subcontractors; a third party may include without limitation any number of venders, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, and so on.
As shown in
The disclosed heat shield assembly and method may be employed during any one or more of the stages of the aircraft manufacturing and service method 400. As one example, components or subassemblies corresponding to component/subassembly manufacturing 408, system integration 410, and or maintenance and service 416 may be fabricated or manufactured using the disclosed heat shield assembly and method. As another example, the airframe 418 may be constructed using the disclosed heat shield assembly and method. Also, one or more apparatus examples, method examples, or a combination thereof may be utilized during component/subassembly manufacturing 408 and/or system integration 410, for example, by substantially expediting assembly of or reducing the cost of an aircraft 402, such as the airframe 418 and/or the interior 422. Similarly, one or more of system examples, method examples, or a combination thereof may be utilized while the aircraft 402 is in service, for example and without limitation, to maintenance and service 416.
The disclosed heat shield assembly and method are described in the context of an aircraft; however, one of ordinary skill in the art will readily recognize that the disclosed heat shield assembly and method may be utilized for a variety of applications. For example, the disclosed heat shield assembly and method may be implemented in various types of vehicle including, e.g., helicopters, passenger ships, automobiles and the like.
Although various embodiments of the disclosed heat shield assembly and method have been shown and described, modifications may occur to those skilled in the art upon reading the specification. The present application includes such modifications and is limited only by the scope of the claims.
Claims
1. A heat shield assembly comprising:
- a frame comprising a plurality of frame members joined together, wherein said plurality of frame members includes a plurality of longitudinally extending frame members, each extending along a primary longitudinal axis of the heat shield assembly, and a plurality of transverse frame members, each perpendicular to the primary longitudinal axis and spaced away from each other, wherein the plurality of transverse frame members are joined to the plurality of longitudinally extending frame members;
- a skin panel directly connected to the frame; and
- a stiffener directly connected to the skin panel, said stiffener comprising a base portion and a bead portion protruding from said base portion, wherein said base portion is directly connected to said skin panel to define a bead volume between said bead portion and said skin panel, wherein said bead portion is positioned between two adjacent ones of said plurality of transverse frame members.
2. The heat shield assembly of claim 1 wherein said skin panel comprises an interior surface and an exterior surface, wherein said plurality of frame members are directly connected to said interior surface.
3. The heat shield assembly of claim 2 wherein said base portion of said stiffener is directly connected to said interior surface.
4. The heat shield assembly of claim 1 wherein said skin panel is a base skin panel, and further comprising a first side skin panel directly connected to said plurality of frame members and a second side skin panel directly connected to said plurality of frame members.
5. The heat shield assembly of claim 1 wherein said stiffener comprises a monolithic body, and wherein said monolithic body defines said base portion and said bead portion.
6. The heat shield assembly of claim 1 wherein said stiffener comprises a fillet between said base portion and said bead portion.
7. The heat shield assembly of claim 1 wherein said base portion is directly connected to said skin panel by a thermal joint.
8. The heat shield assembly of claim 1 wherein said base portion is directly connected to said skin panel by a mechanical fastener.
9. The heat shield assembly of claim 1 wherein said bead portion comprises a continuous curvature.
10. The heat shield assembly of claim 1 wherein said bead portion is elongated along a longitudinal axis.
11. The heat shield assembly of claim 10 wherein said longitudinal axis of said bead portion is substantially aligned with said primary longitudinal axis.
12. The heat shield assembly of claim 10 wherein said longitudinal axis of said bead portion is transverse with respect to said primary longitudinal axis.
13. The heat shield assembly of claim 1 wherein said stiffener further comprises a second bead portion.
14. The heat shield assembly of claim 13 wherein said second bead portion intersects said bead portion.
15. An aircraft comprising a pylon fairing, wherein said pylon fairing comprises said heat shield assembly of claim 1.
16. The heat shield assembly of claim 1 wherein said plurality of longitudinally extending frame members includes at least a first upper longitudinally extending frame member at a first side of the heat shield assembly, a second upper longitudinally extending frame member at a second side of the heat shield assembly, and a first lower longitudinally extending frame member at the first side of the heat shield assembly, wherein each transverse frame member is supported by at least the first upper longitudinally extending frame member, the second upper longitudinally extending frame member, and the first lower longitudinally extending frame member.
17. The heat shield assembly of claim 16 wherein said skin panel is a base skin panel directly connected to lower portions of each of the plurality of transverse frame members.
18. The heat shield assembly of claim 1 wherein the skin panel is formed from a metallic material.
19. The heat shield assembly of claim 1 wherein adjacent ones of the plurality of frame members are jointed together.
20. The heat shield assembly of claim 1 wherein each transverse frame member of the plurality of transverse frame members is directly joined with two of the plurality of longitudinally extending frame members.
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Type: Grant
Filed: Mar 14, 2016
Date of Patent: Oct 1, 2019
Patent Publication Number: 20170259906
Assignee: The Boeing Company (Chicago, IL)
Inventors: Thomas J. Connelly (Bellevue, WA), Linda M. Li (Seattle, WA)
Primary Examiner: Medhat Badawi
Assistant Examiner: Vicente Rodriguez
Application Number: 15/068,924
International Classification: B64C 3/36 (20060101); B64D 29/02 (20060101); B64C 1/12 (20060101); B64C 1/40 (20060101); B64D 27/26 (20060101);